Introduction To The NODC Ocean Heat Content Anomaly Data For Depths Of 0-2000 Meters
The National Oceanographic Data Center (NODC) recently posted a new Ocean Heat Content (OHC) anomaly dataset on its website. It is available on annual and quarterlybases, along with the data for its standard and documented dataset that covers depths of 0-700 meters. I looked for but was not able to find any papers (in any state of publication) that supported the new OHC data for 0-2000 meters. We’ll just have to wait and see how the NODC intends to present this dataset.
The data for the depths of 0-700 meters is, of course, documented in the paper Levitus et al (2009) “Global ocean heat content (1955-2008) in light of recent instrumentation problems”. Refer to Manuscript. It was revised in 2010 as noted in the October 18, 2010 post Update And Changes To NODC Ocean Heat Content Data. As described in the NODC’s explanation of ocean heat content (OHC) data changes, the changes result from “data additions and data quality control,” from a switch in base climatology, and from revised Expendable Bathythermograph (XBT) bias calculations.
COMPARISON OF GLOBAL OHC ANOMALIES: 0-700 METERS VERSUS 0-2000 METERS
Figure 1 compares the quarterly NODC OHC anomaly data for the depths of 0-700 meters and 0-2000 meters on a global basis. As noted on the illustration, the most obvious divergence between the two datasets occurs during the ARGO era. This is the period when ARGO floats became the dominant means of sampling of ocean temperatures and salinity at depth.
Figure 1
If we limit the comparison to the period from 1970 to 1999, Figure 2, we can see that there is basically no difference in the linear trends. There are minor differences from year to year, but the two datasets appear to be basically the same. Why?
Figure 2
There are extremely few observations prior to the year 2000 at depths greater than 1000 meters. This is illustrated in Figure 3. (Note that NOAA Climate Prediction Center Data Distributionwebpage breaks down the temperature profiles into depths of 0-250 meters, 250-500 meters, 500-1000 meters and 1000-5000 meters. Those depths don’t agree with the depths presented by the NODC for its Ocean Heat Content anomaly data.)
Figure 3
And Animation 1 shows a series of annual maps of the locations of temperature profiles from 1979 to 2005 for the depths 1000-5000 meters. As illustrated, there is also very little spatial coverage at these depths until the introduction of the ARGO floats.
Animation 1
As a reference, Figure 4 shows the number of temperature profiles for depths of 250 to 500 meters. There were between 2000 to 5000 temperature profiles per month between the late 1970s and the late 1990s at these depths before the ARGO floats were deployed. Note that the TAO/TRITON project (red curve) shows temperature profiles that were initially for the equatorial Pacific (coordinates approximately 8S-9N, 137E-95W). Those buoys were deployed for the study of El Niño and La Niña events. The locations were later expanded to include portions of the Tropical Atlantic and Indian Oceans under the PIRATA and RAMA projects. Refer to the TAO Project Global Arraywebpage. So while there are a good number of temperature profiles for the TAO project, they are limited in their location.
Figure 4
Figure 5 illustrates the difference between the two NODC Global Ocean Heat Content (OHC) datasets, where the 0-700 meter data has been subtracted from the 0-2000 meter data. Also referring back to Figure 3, the difference between the two datasets seems to increase in concert with the number of temperature samples at depths greater than 1000 meters. It appears as though the divergence of the 0-2000 meter dataset from the 0-700 meter data since around 2000 could be caused by the increased number of samples at depth and the increased spatial coverage of the ARGO floats, as shown in the animations. The impacts on short-term and long-term trends of the increased number of samples at depths greater than 700 meters and the impact of the increased area of observations should be determined. (A study such as that is well beyond my capabilities.) Maybe it will be documented in the NODC paper that accompanies the 0-2000 meter dataset.
Figure 5
Keep in mind, before the ARGO era, there were very few ocean temperature observations at any depth in the Southern Hemisphere south of about 40S. For example, Animation 2 is a gif animation of maps that illustrate the locations of temperature profiles for depths of 0-250 meters, 250-500 meters, 500-1000 meters, and 1000-5000 meters for the year 1995.
Animation 2
And Animation 3 shows the same series of temperature profile maps but for the year 2005.
Animation 3
A COUPLE OF QUESTIONS FOR READERS
Were the Expendable Bathythermograph (XBT) probes with wire lengths of 760 meters the most commonly used XBT probes before the ARGO era? Is this the reason the NODC originally limited the depth to 700 meters for the Ocean Heat Content anomaly data? Does anyone recall a paper that presents this? I had always assumed the depth of 700 meters was selected due to the number of and locations of observations, but I have never seen it stated in a paper.
LONG-TERM TRENDS PER OCEAN BASIN
When I originally prepared the graphs for this post, I could find no reason to present the long-term trends for the individual ocean basins of the 0-2000 meter data. The reason being, in some respects, the NODC OHC data for 0-2000 meters appears to me to simply be a 0-2000 meter OHC dataset spliced onto a 0-700 meter dataset. But on further thought, my failure to present the data might be thought by some as an attempt on my part to hide something. So Figure 6 (0-2000 meters) and Figure 7 (0-700 meters) are long-term trend comparisons of the Ocean Heat Content anomalies for the individual ocean basins as presented by the NODC. The most obvious similarity is that the long-term trends of the North Atlantic Ocean Heat Content are significantly higher than other ocean basins in both datasets, and in both, the North Atlantic Ocean Heat Content peaked in 2004. After that, there are significant declines. One would think this would lead researchers to examine the effects of the Atlantic Multidecadal Oscillation and Meridional Overturning Circulation on North Atlantic Ocean Heat Content observational data, yet, as far as I know, this is an area unexplored by climate scientists.
Figure 6
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Figure 7
ARGO-ERA TRENDS PER OCEAN BASIN
The ARGO-era (2003 to present) linear trends per ocean basin for the depths of 0-2000 meters and 0-700 meters are shown in Figure 8 and 9, respectively. Like the trends for the 0-700 meter data, the South Atlantic and Indian Ocean are the only basins with significantly positive linear trends for the 0-2000 meter Ocean Heat Content data. And also like the trends 0-700 meter data, the linear trends of the 0-2000 meter Ocean Heat Content anomalies in the North Atlantic and South Pacific are negative. The linear trends for those two ocean basins are less negative for 0-2000 meter depths than they are for 0-700 meter depths, indicating that the declines at depths of 0-700 meters are greater than the increases at the 700-2000 meter depths. Considering there is less than a decade of ARGO-era data with “full” coverage, there is no need to speculate about the cause. Note also that the trend for the North Pacific OHC anomalies is basically flat for the 0-2000 meter data, and that the same holds true for the 0-700 meter data.
Figure 8
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Figure 9
CLOSING COMMENTS
The undocumented (as of this writing) NODC 0-2000 meter Ocean Heat Content dataset appears as though it was prepared to show that Global Ocean Heat Content continues to rise during the ARGO era, and that it is intended to counter the argument that Global Ocean Heat Content has flattened during the ARGO era as shown in the NODC 0-700 meter dataset.
Due to the extremely limited number of observations at depths of 1000-5000 meters (shown in Figure 3 and in the animations), the 0-2000 meter Ocean Heat Content dataset should be used with great caution. It appears to me to be an ARGO-era 0-2000 meter Ocean Heat Content dataset spliced onto a long-term 0-700 meter dataset. For this reason, I, personally, would not expend the effort to analyze the long-term (pre-ARGO era) 0-2000 meter NODC OHC data beyond what has been presented in this post.
Each time I see the claim (based on many assumptions) by anthropogenic global warming proponent scientists that the rise in ocean heat content at depth “will come back to haunt us” I wonder why those same scientists have not bothered to attempt to document how much of the rise in OHC from the 1970s to the early 2000s (0-700 meters) was caused by the deep oceans upwelling warmer anomalies from past decades, other than the fact that there’s no data for them to do so. Could they believe that multidecadal variability is limited to Sea Surface Temperatures and does not impact temperatures at depth? Or is their intent to have the unsuspecting public believe it?
What a lot of nonsense has been put here about the ocean mass temperature.
Bill Illis gave you a hint of the reason why the ocean is cold.
Not completely correct about the surface temperature.
The surface water is warm because of the SUN. As the water mass is cold because of the lack of the SUN at the Poles.
It’s the SUN….(after the continent distribution on the globe has been considered)!
@Bob Tisdale,
Thanks for the color changes, they work better for me as well.
Stephen Wilde says:
October 25, 2011 at 5:43 am
I agree with the principle that ocean water is like a greenhouse gas on steroids but I totally don’t understand how that’s analogous to a hot water bottle.
Last post (I’m sure I’ll hear a thank god or two!).
Dave Springer. How do you get -18C for the black body temperature of the earth?
Incoming flux from the sun is alleged to be 1360 w/m² (give or take a bit), SB constant is 5.67 X 10^-8, 4 times radiating surface versus absorbing surface, so T^4=1360/(4*(5.67X10^-8)), T=278 K or + 5C for a perfect blackbody radiator/absorber. Incoming solar flux would have to less than 1,000 w/m² for -18C. The -18C value includes albedo or reflectance, which would mean we are not talking about a black body.
JE
Bill Illis says:
October 25, 2011 at 5:48 am
“Climate scientists often taken advantage of their audience by not pointing out that global temperature change is only half that of polar temperatures. See the Eocene for an example of that as well.”
Patently false. The south pole has not warmed up at all. Back to the drawing board, Bill.
“I agree with the principle that ocean water is like a greenhouse gas on steroids but I totally don’t understand how that’s analogous to a hot water bottle.”
It’s as good an analogy as a greenhouse but neither analogy is perfect. A hot water bottle stores energy and releases it over time as do the oceans.
“The surface water is warm because of the SUN. As the water mass is cold because of the lack of the SUN at the Poles”
Correct so far as it goes. However if one were to change the energy value of the latent heat of evaporation by changing surface pressure then the whole mass would still change equilibrium temperature. Lower atmospheric pressure would cool the oceans and higher pressure would warm them.
No atmosphere = no oceans because they would evaporate away to space in a jiffy.
John Eggert says:
October 25, 2011 at 8:25 am
“The -18C value includes albedo or reflectance, which would mean we are not talking about a black body.”
I thought you were referring to the ocean surface as a blackbody not the center of mass of the atmosphere as the blackbody surface. Sorry about the confusion. The ocean surface of course approximates a black body very well but it receives about 30% less incident radiation than the top of the atmosphere. Its blackbody temperature is -18C when you calculate by actual amount of incident radiation it receives. Yet it is far warmer than that. It’s warmer not because of greenhouse gases but because water itself is a greenhouse fluid.
I’m sorry Mr. Tisdale, but your response to Lazyteenager is disingenuous to say the least. Both the title of this post and the caption accompanying figure 1 suggest willful deceit on the part of the NODC. And this is also the idea that numerous commenters have gotten from your post. You’re speaking out of both sides of your mouth, Mr. Tisdale. Please have the decency to either be straightforward in your accusations, or change the title of this piece and any other passage that might allude to fraud, deceit or conspiration, and correct the wrong impression that many commenters here have gotten.
Thank you.
Excellent discussion regarding the enormous potential heat sink capacity of the ocean and how small changes in cold upwelling or surface mixing can cause large surface temperature changes.
The implications of this also provides a mechanism of climate control. It is relatively easy to divert flow or induce currents (which also makes it very dangerous). The ocean’s chill is a resource that is completely untapped by Man. Very large, low energy, circulation pumps enhanced by siphon properties, are “off the shelf”, “in service”, technology and we are already dam builders.
I have no idea, however, how we get around the problem of:
– Those that control the weather/climate… control the world
– How will we ever agree (geographically) on it’s use? Certainly not the U.N., they represent nobody, no-how, no where.
Until we have useful models – we can’t start the debate! GK
Bill Illis says:
October 24, 2011 at 5:07 pm
1.0 Watt/m2 over the entire Earth over 1 year equals 1.61 10^22 joules.
I would suggest you are using the wrong approach. The one Watt over land would be a constant forcing from a black body into the gaseous shell of an open system. At the point radiative or temperature equilibrium, it would be a constant throughput and not a cumulative energy value.
You could notionally use Stefan–Boltzmanns law to calculate the rise needed in the temperature of the black body to give you the one Watt but only if you know the base temperature or radiant value of the black body. This should give you the potential temperature of the gas but the joule value would be dependent on its specific heat capacity.
Rick C says:
……
Maybe somebody can explain to me what mechanism would allow heat to reach 2000 meters from the less than 1 mm skin depth of infrared penetration in less than 11 days….
_____________________
MAGIC! or Schrodinger’s cat is in a playful mood again.
JCL says: “I’m sorry Mr. Tisdale, but your response to Lazyteenager is disingenuous to say the least. Both the title of this post and the caption accompanying figure 1 suggest willful deceit on the part of the NODC. “
The title of my post is “Introduction To The NODC Ocean Heat Content Anomaly Data For Depths Of 0-2000 Meters”:
http://bobtisdale.wordpress.com/2011/10/24/introduction-to-the-nodc-ocean-heat-content-anomaly-data-for-depths-of-0-2000-meters/
Please advise where in that title I “suggest willful deceit on the part of the NODC”?
And I will assume the caption in Figure 1 you’re complaining about is the question “Is The New 0-2000 Meter Dataset Being Introduced To Hide The Flattening Of The 0-700 Meter Data Since 2003?” How in your mind could that question imply “fraud, deceit or conspiration,” as you later write in your comment? It’s the basic question that came to mind when I plotted the 0-700 meter and 0-2000 meter datasets side by side. The one dataset flattens and the other doesn’t. And it’s the basic question that came to mind when I considered the 0-2000 meter dataset is basically source data free from 1000 to 2000 meters prior to the ARGO era.
If you’re not aware, AGW proponents are already playing with and commenting on the NODC 0-2000 meter OHC dataset. For instance, JosHag states in his 20:17 PM on 15 October, 2011 comment on the “Ocean Heat Poised To Come Back And Haunt Us?” post at SkepticalScience, “When you subtract the ocean heat uptake values of the two datasets, you should get an idea in which period the deeper ocean gains more heat than the upper ocean…
http://www.skepticalscience.com/Ocean-Heat-Poised-To-Come-Back-And-Haunt-Us-.html#65446
And of course, his graph shows a recent increase in Heat Uptake. JosHag doesn’t understand that the 0-2000 meter dataset is basically data free at depths of 1000-2000 prior to the ARGO era and that that is the reason he’s getting the results he’s getting.
Further on that thread, Jsquared in his 20:42 PM on 17 October, 2011 comment…
http://www.skepticalscience.com/Ocean-Heat-Poised-To-Come-Back-And-Haunt-Us-.html#65531
…notes, “The heating of the deep ocean after 2001 or so is indeed mostly occurring in the southern ocean, as predicted by the models used by Meehl et al.”
But Jsquared fails to understand that there is little to no data at any depth in the Southern Hemisphere south of 40S prior to the ARGO era. He’s making assumptions that are not supported by data.
Regarding your suggestion that I change the post to satisfy your concerns, I have no intent of altering the content of the post. I do not see where I’ve suggested “fraud, deceit or conspiration” on the part of the NODC.
To me, the NODC did themselves a disservice by posting this dataset before the paper. They have opened the door wide for misinterpretations by the likes of JosHag and Jsquared.
As I wrote in the opening paragraph, “We’ll just have to wait and see how the NODC intends to present this dataset.”
The concept of warm water “downwelling” to the ocean depths needs to be challenged – there seem to be some very strange ideas on this, not least the desperate idea that Trenbeth’s missing heat is winging its way to the depths. Here are my current thoughts on the subject – please take pot-shots as appropriate!
1. Major downwelling that is significant for the thermo-haline circulation (THC) ONLY involves water that is very cold – near freezing, and which has become more saline due to ice formation. This happens only at specific locations – the Norwegian sea in the Arctic, and one or more locations in the Southern Ocean between Australia and Antarctica. ONLY near freezing and super-saline water has the density to propel it to the bottom of the ocean. Warm water – or even not quite freezing water of average salinity – NEVER downwells to the bottom. Ever.
2. The deep ocean layer down to the bottom, which globally has an average depth of about 4 km but is up to 10 km deep in places, should be considered as a separate body of water to upper ocean water, and has a separate system of circulation and currents (the THC); often the surface currents and underlying THC currents are going in different and even opposite directions. They dont mix all that much, only exceptionally at locations and times of upwelling (bottom water visits the top) or downwelling (top water visits the bottom).
3. Movement downwards of warmer water does happen due to turbulent mixing, assisted by various winds, gyres and currents, down possibly to even 1-2000 m. But not to the ocean bottom. Thus downward movement of warmer water should be considered as part of mixing of the upper to mid ocean depths, but it is completely separate from downwelling in the true sense (1).
4. I agree with Bill Illis that – for as long as earth has had an ocean – the bottom water is always at about 0-3C as today, even back in the mesozoic / palaeozoic. This is partly due to the huge gravitational pressure on bottom water. Increasing bottom water temperature would require much more energy to lift the whole water column due to thermal expansion than the energy needed for the temperature change itself. So however warm it is on the surface, the bottom is always 0-3C.
5. The reason that the impossible idea of warm water somehow forcing its way down to the ocean floor displacing cold water of greater density – has caught on, is that it provides a mechanism for climate heat “memory”. For instance one observes a time lag of up to 1000 years between climate warming and CO2 increase, e.g. from the ice cores. Thus the idea of water warmed at the surface descending to the depths to emerge centuries later is appealing. It is also a potential refuge of last resort for CAGW – Trenberth’s missing heat hiding at the ocean bottom to re-emerge years later. But this does not happen.
6. However climate warming at the surface can affect long term ocean circulation in ways other than the impossible storage of warm water at the ocean floor. There is a connection – with time delay – between downwelling and upwelling, so that for instance, surface warming would reduce downwelling, which may eventually (after a delay) cause a reduction in upwelling, and the overal result is more stable stratification globally, less vertical mixing. Change to the pattern and rate of downwelling can also have complex hard-to-predict changes on the THC pattern.
7. If the rate of downwelling changes intermittently, e.g with PDO / AMO phases or solar phases, then the whole deep circulation system might behave like a nonlinear oscillator under periodic forcing. Thus cycles of alternate increased and decreased vertical mixing globally might be the response to periodic changes in downwelling in the previous hundreds or even thousands of years.
Most of this is of course pure conjecture.
No atmosphere = no oceans because they would evaporate away to space in a jiffy.
Dave Springer says:
October 25, 2011 at 8:53 am
John Eggert says:
October 25, 2011 at 8:25 am
“The -18C value includes albedo or reflectance, which would mean we are not talking about a black body.”
I thought you were referring to the ocean surface as a blackbody not the center of mass of the atmosphere as the blackbody surface. Sorry about the confusion. The ocean surface of course approximates a black body very well but it receives about 30% less incident radiation than the top of the atmosphere. Its blackbody temperature is -18C when you calculate by actual amount of incident radiation it receives. Yet it is far warmer than that. It’s warmer not because of greenhouse gases but because water itself is a greenhouse fluid.”
This is so basic, and so poorly understood. Each wavelength of incoming TSI has a different residence time within the atmosphere, land and ocean. This residence time is of course affected by it own inherent properties as well as all of the material it encounters. Only two things can effect the energy content of any system in a radiative balance. Either a change in the input, or a change in the “residence time” of some aspect of those energies within the system.” The longer the “residence time” the greater the energy sink capacity. The greater the energy capacity, the longer it takes for any change to manifest, and in the case of OHC this involves years, not annually. We simply do not know the residence time of the various SWR entering the ocean, therfore we do not know the affect of long term changes in the solar cycle. We do know that the residence time of energy entering the oceans is far longer then the residence time of energy in the atmosphere, therfore any change in the atmosphere (GHG) which reduces SWR entering the oceans may raise the atmosphere temperature, but, over time, cool the oceans.
“For instance one observes a time lag of up to 1000 years between climate warming and CO2 increase, e.g. from the ice cores. Thus the idea of water warmed at the surface descending to the depths to emerge centuries later is appealing. It is also a potential refuge of last resort for CAGW –”
Actually it is potentially fatal for CAGW because it provides a mechanism whereby energy resurfacing from the MWP could contribute to the warming of the tropopshere since the the LIA AND cause changes in CO2 absorption rates by the oceans that could result in a steady rise in atmospheric CO2 as per the Mauna Loa record. The steadiness of that rise despite variations in weather, climate and human CO2 emissions is a conundrum that needs to be addressed.
Such a process would leave little need to propose a human contribution.
It is not necessary for warm water to be advected downward to achieve a measurable effect because the thermal capacity of water is so large compared to that of air. All that would be needed would be for a solar induced warming of the system to introduce small temperature discontinuities along the horizontal route of the THC.
Thus a few hundred years of elevated solar activity could well feed slightly less cold water into the THC and slightly warmer water upwelling some 1000 years or so later.
phlogiston, regarding your October 25, 2011 at 1:23 pm comment, just a thought. Consider that the meridional overturing circulation, the subducting currents, already exist, that they’re already in motion. They have momentum. Wouldn’t it take something catastrophic to stop them?
Bob Tisdale says:
October 25, 2011 at 2:58 am
philip Bradley says: “Infrared penetration is irrelevant. The mechanism is that a warmer atmosphere impedes evaporation and therefore warms the oceans.”
Please supply links to papers that document this using observational data. Your hypothesis sounds very odd to me.
My point was that (increased) downwelling IR heating the top few mm of the oceans is not the mechanism by which the oceans warm.
The mechanism is solar radiation into the oceans, which is then released to the atmosphere primarily by evaporation. Given solar radiation is constant, the oceans warm by impeded heat loss to the atmosphere.
The main factors that effect the rate of evaporation and hence ocean heat loss are air turbulence and temperature gradient.
IR heating at the top of the ocean will have a warming effect, but the primary mechanism is that a reduced temperature gradient will reduce evaporation.
Actually measuring what happens within a few mm of the ocean surface is nigh well impossible.
RC covered this
[Link deleted by mistake. Please re-post. ~dbs, mod.]
Stephen Wilde
Rather than a change in the temperature of upwelling water, I would think it more likely that the rate, timing and maybe locations of upwelling might change.
Possibly both. Wouldn’t it be changing temperature differentials that would cause those other changes?
Bob Tisdale
Yes, thus the MOC and THC etc. really are quasi-permanent features of the earth. However rates of flow and spatial paths can change to some extent presumably.
The subducting downward arm of the MOC is the downwelling in the Norwegian sea.
Damn. Have to prove myself a liar.
phlogiston says:
October 25, 2011 at 1:23 pm
“The concept of warm water “downwelling” to the ocean depths needs to be challenged . . .”
Have you fully accounted for salinity in that comment? Saltier water, such as one gets from a hot ocean, is denser than less salty water, such as occurs where ice is melting. Which density difference is greater? Hot / cold or sweat / salty? This is a question that can be answered to a very high degree of accuracy.
Some other interesting things there. If the only source of heating in the ocean were the atmosphere, your argument (point 4) about mass of the ocean stopping heat transfer would be off on only one account. Convection (“downwelling”) is not the only method of heat transfer. Nor is downwelling the only source of convection. There is also conduction, and as you point out, there are currents of the depths and currents of the shallows. Even if these do not mix, they touch and hence heat will move from hot to cold. The warming by conduction occurs from top to bottom, so the dense thing doesn’t apply. However, the atmosphere is not the only source of heat. The crust itself is a small, almost trivial source of heat. But it isn’t entirely trivial and it is constant. You cannot continually add energy to something without raising the temperature. That heat went somewhere. If it did heat the water, there would be upwelling of heat, resulting in convective heat transfer. So again, we are faced with the question. How can something be warm on one side, warm on the other, cold in the middle, for billions of years?
MartinGAtkins says:
October 25, 2011 at 10:46 am
Bill Illis says:
October 24, 2011 at 5:07 pm
1.0 Watt/m2 over the entire Earth over 1 year equals 1.61 10^22 joules
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This is more of a definition than a calculation. 1.0 Watt = 1 Joule/second. So it is just how many seconds there are in a year times the square metres of the Earth. It is the generally accepted value.
I’m really just trying to put some context around the OHC figures which are always quoted in 10^22 joules while climate science works in Watts/m2.
The 1.61 10^22 joules just gives a reference so we can go back and forth between the two and tell how much the OHC is supposed to be rising.
Here is another frame of reference:
– 1.61 10^22 joules = 40,497,031,894,556,800,000,000,000,000,000,000,000,000
individual photons of sunlight or 0.4% of the total energy received by the Earth from the Sun in a year.
philip Bradley says:
October 25, 2011 at 3:54 pm
“Given solar radiation is constant, the oceans warm by impeded heat loss to the atmosphere.”
Solar radiation is not constant, it varies considerably, and even more at the surface. Even the GHG, CO2 affects TSI at the surface.
Thanks to Bob Tisdale for another well done, thought provoking analysis of oceanic temperatures. It launched lots of interesting commentary. Some of comments most interesting to me were offered by JeffD (“How much would you think vulcanism plays into the temp of oceans?”) and responses by
John Eggert (“… about 0.2 W/m^2) and
Dave Springer (“… the more indepth calculation is 0.1 W/m^2. The ocean loses about 200 W/m^2 at the surface so a tenth of a watt added at the bottom is still insignificant in comparison.”)
Should not the question of ‘significance’ regarding vulcanism as a subsea heat source be evaluated relative to the alleged/postulated TOA heat transferred to deep water rather than relative to ocean surface heat transfers? I think so. And, assuming JeffD is/was the term “vulcanism” to mean volcanic eruptions I believe the discussion merits expansion to include all forms of geothermal heat releases, including subsea hydrothermal venting, non-eruptive magma and lava emissions, and explosive volcanic blasts.
A source cite is not handy but I seem to recall reading about a 44 TW (10^12 Watts) estimate of Earth’s “heat engine” production from radiogenic (radioactive decay) processes. http://www.sciencemag.org/content/321/5897/1825.abstract suggests “Sub-seafloor hydrothermal convection at mid-ocean ridges transfers 25% of the Earth’s heat flux ….” I read that estimate as applying to ocean ridge hydrothermal convection transfers only (exclusive of vulcanism) and implying hydrothermal transfer of ~11 TW of heat into the oceans. Disregarding “vulcanism”, those estimates imply crustal conductive heat transfer of 33 TW. With oceans covering ~ 70% of earth’s surface, 23.1 TW of that residual 33 TW would transfer into ocean waters. Geothermal heat transfers of 11 TW + 23.1 TW = 34.1 TW in ocean waters is implied or about 77% of the heat generated by earth’s radiogenic “heat engine.” Including consideration of magma and lava emissions (1200°C) would almost surely increase the share of earth’s total geothermal heat flowing into oceans. http://volcano.oregonstate.edu/eruption-rates suggests 3/4 of all magma and lava production occurs along/around mid-oceanic ridges.
With average mid-ocean ridge-crest water depth of ~2,500 meters, it appears plausible that more than 17 TW of geothermal energy flows from the mantle/crust into ocean waters at depths greater than 700 meters on a relatively steady basis. But, there is little reason to presume it is constant or “steady state” heat production or transfer according to http://www.columbia.edu/itc/ldeo/v1011x-1/jcm/Topic3/Topic3.html.
I haven’t done the math to generate an estimate comparable to those provided by John Eggert and Dave Springer but in light of the above believe their estimates could be on the low side due to reliance on too little energy input as well as due to likely focus on too much water (total ocean water volume vs waters deeper than 700 meters).
Solar radiation is not constant, it varies considerably, and even more at the surface. Even the GHG, CO2 affects TSI at the surface.
TSI = Total Solar Irradiance or Total Solar Insolation
I accept that there is not enough variation in TS Irradiance to explain the apparent climate warming.
TS Insolation is a whole other matter and involves multiple factors, including the elephant in the climate room – clouds.
Anyway my intent in using ‘given’ was to avoid a debate about changes in Total Solar Insolation.
The deleted RC is link is
http://www.realclimate.org/index.php/archives/2006/09/why-greenhouse-gases-heat-the-ocean/
RC is generally good on the basic science. They get unreliable when discussing evidence for AGW.